Final answer:
Intertidal organisms face challenges with temperature fluctuations in addition to changes in salinity and water levels. They adapt with specialized features such as tough exoskeletons to survive in the intertidal zone, a region with dynamic environmental variations.
Step-by-step explanation:
Besides fluctuations in salinity and water levels, intertidal organisms must also withstand wide variations in temperature, pH, light intensity, and nutrient levels. Among these, the correct answer to the challenges faced by intertidal organisms is temperature.
Intertidal zones are dynamic environments where organisms are exposed to a range of abiotic factors due to the constant movement of water and exposure to air. Organisms must adapt to varying temperatures, which can change drastically between the high tide and low tide as water acts as a buffer and air does not. Other factors affecting these organisms include the intensity and duration of sunlight exposure, which affects the phytoplankton populations that serve as a base for the food web in these zones.
Therefore, to thrive in the intertidal zone, organisms such as barnacles and crustaceans have developed physical adaptations like tough exoskeletons to protect against desiccation and wave action.